Atomically Dispersed Manganese on Carbon Substrate for Aqueous and Aprotic CO₂ Electrochemical Reduction.

Abstract

CO₂ utilization and conversion are of great importance in alleviating the rising CO₂ concentration in the atmosphere. Here, a single-atom catalyst (SAC) is reported for electrochemical CO₂ utilization in both aqueous and aprotic electrolytes. Specifically, atomically dispersed Mn-N₄ sites are embedded in bowl-like mesoporous carbon particles with the functionalization of epoxy groups in the second coordination spheres. Theoretical calculations suggest that the epoxy groups near the Mn-N₄ site adjust the electronic structure of the catalyst with reduced reaction energy barriers for the electrocatalytic reduction of CO₂ to CO. The resultant Mn-single-atom carbon with N and O doped catalyst (MCs-(N,O)) exhibits extraordinary electrocatalytic performance with a high CO faradaic efficiency of 94.5%, a high CO current density of 13.7 mA cm^-2 , and a low overpotential of 0.44 V in the aqueous environment. Meanwhile, as a cathode catalyst for aprotic Li-CO₂ batteries, the MCs-(N,O) with well-regulated active sites and unique mesoporous bowl-like morphology optimizes the nucleation behavior of discharge products. MCs-(N,O)-based batteries deliver a low overpotential and excellent cyclic stability of 1000 h. The findings in this work provide a new avenue to design and fabricate SACs for various electrochemical CO₂ utilization systems.